Recently, there has been increasing demands for developing a communication system which can copy electric data containing personal information such as data of a telephone book and store into a mobile phone, or which makes it possible to read and write electric medical sheets at a hospital or a pharmacy, or which makes it possible to read or request electronic resident register data such as certificates of residence and family registers, or which can transfer, copy and store data relating to personal hobby (various kinds of data such as music and images) to and in an own mobile phone, etc., or which can read and store amount of money data for a prepaid of an automatic vending machine, etc. in a desired electronic device, or which can be used as a pass, etc. for passing through a wicket at an amusement park or a station, etc. In other words, there has been increasing demands for developing the communication system (hereinafter called as a proximity contactless communication system) which is made in contact to or brought close so as to be contactable to a communication partner thereby to perform a communication (to be concretely, by using the action of electric field or magnetic field).
To this end, there has been investigated as to the developments of various kinds of portable communication devices each having a proximity contactless communication function (hereinafter called as “a portable communication device with a proximity contactless communication function”), each of which can perform the proximity contactless communication with a proximity contactless communication device disposed outside (hereinafter called as “an external proximity contactless communication device”) or a proximity contactless communication card disposed outside (hereinafter called as “an external proximity contactless communication card”) which serves a partner side at the time of performing the proximity contactless communication (see patent document 1, for example).
As one of the portable communication devices accorded to such the proximity contactless communication system, there is proposed a mobile phone 100 with the proximity contactless communication function as shown in FIG. 16, for example.
As shown in the figure, the mobile phone 100 with the proximity contactless communication function is configured in a manner that a casing 101 is formed in a straight shape (of course, a fordable shape may be used) and contains therein not only an antenna 102 for the mobile phone for transmitting and receiving a signal to and from a base station disposed outside of the figure but also an antenna 103 for the proximity contactless communication for performing the proximity contactless communication with an external proximity contactless communication device 200, etc.
On the other hand, the external proximity contactless communication device 200 includes an antenna 201 for the proximity contactless communication for performing the proximity contactless communication.
Incidentally, in the figure, a symbol 106 depicts a battery chamber which houses a battery unit 105 for feeding therein and is closed by a battery lid 104.
The mobile phone 100 with the proximity contactless communication function is configured so as to perform communication or data communication with a base station via the antenna 102 for the mobile phone. The mobile phone 100 is also configured so as to perform the proximity contactless communication between the antenna 103 for the proximity contactless communication within the casing 101 of the mobile phone 100 and the antenna 201 for the proximity contactless communication within the casing of the external proximity contactless communication device 200 when the antenna 103 for the proximity contactless communication provided near the one surface (the upper surface in FIG. 16) within the casing 101 of the mobile phone 100 is made in contact to or brought close to and placed over the external proximity contactless communication device 200.
However, in the mobile phone 100 with the proximity contactless communication function, as described above, the antenna 103 for the proximity contactless communication is disposed at the one surface of the casing 101 of the mobile phone 100. Thus, in the case of performing the proximity contactless communication, when the surface other than the one surface of the casing 101 is made in contact to or brought close to and placed over the device, it is often the case that proximity contactless communication error arises due to the directivity of the antenna 103 for the proximity contactless communication. As a result, there is a problem that the convenience is not good in a point that the particular surface of the casing 101 is required to be placed over the device.
Therefore, as described in a patent document 2, for example, there is proposed such a structure that two antennas for proximity contactless communication are provided in parallel to each other so that the proximity contactless communication can be performed without being limited to the one surface. However, according to such a configuration, since the antennas are provided in parallel to each other, the total inductance value of the antennas decreases. In this case, in order to resonate the antenna at a desired frequency, it is necessary to increase the inductance component of the antenna or to increase the constant value of a resonance capacitor.
In general, in order to increase the inductance component of the antenna, it is necessary to increase the area of the antenna and increase the number of turns of a conductor constituting the antenna. However, it is difficult to increase the areas of the plural antennas in a small-sized communication device such as the portable communication device. Further, when the constant value of the resonance capacitor is made large, there arises a problem that the gain of the antenna for proximity contactless communication reduces and so a distance capable of performing the proximity contactless communication reduces.
Thus, as shown in a patent document 3 and a patent document 4, for example, when the antenna for proximity contactless communication is configured in an L-shape, the proximity contactless communication can be performed as to two surfaces or more without being limited to one surface without reducing the inductance value of the antenna.
However, according to such a configuration, with respect to only one surface, in the case of performing the proximity contactless communication by placing this surface in parallel to the antennal of the external proximity contactless communication device, since there is no antenna at the corner portion of the L-shape, the magnetic flux density at the one surface is reduced as compared with the case where the antenna loop is configured by only one surface. As a result, there arises a problem that a distance capable of performing the proximity contactless communication reduces.
Thus, as described in a patent document 5, for example, when an antenna for proximity contactless communication is formed in a loop shape at each of six surfaces, the proximity contactless communication can be performed at not only one surface but also the respective surfaces. Simultaneously, when considering each one of the respective surfaces, since the each surface forms the loop, the reduction of the magnetic flux density can be prevented and the distance capable of performing the proximity contactless communication can be maintained effectively.
However, according to this configuration, when the antennas at the plural surfaces are influenced by the magnetic fluxes, the currents generated at the respective antennas flow in opposite directions and so there arise a problem that the proximity contactless communication error occurs.    Patent document 1: JP-A-2002-236901 (page 2, right column, [0002])    Patent document 2: JP-A-2001-28037    Patent document 3: JP-A-08-44833    Patent document 4: JP-A-11-316806    Patent document 5: JP-A-2001-319206